Gender roles and expectations in countries of origin and countries of destination have an effect on the decision of migration and sex composition of various types of migration flows. In many cases, men make autonomous decisions to migrate, while women migrate as part of family strategies (United Nations, 2006). However, increasingly women migrate on their own and not only to accompany or join family members. In OECD countries, for example, the share of women has increased in recent migration flows in countries where labour migration plays an important role in addressing needs in the domestic service and long-term care sectors (OECD, 2008). In some of the countries with opportunities for jobs traditionally considered “female” types, many women are able to secure jobs more rapidly than their partners, who would later follow with the children (UNDP, 2009). However, in countries that permit only temporary migration and when admission is limited to occupations dominated by men (for example, construction workers or miners), the share of men among immigrants may be higher (United Nations, 2006).

At the global level, about half of the international migrants are women, a share slightly higher than in the past (United Nations, 2010a; 2010b). However, there are great variations by region. For example, countries in Africa, Western Asia and Southern Asia have a lower share of women among migrants (United Nations, 2010a; 2010b). The share of women among migrants in OECD countries is higher among migrants from Asia and lower among migrants from Africa and some countries in Latin America (OECD, 2008). The relative propensity of women in Latin American countries to migrate across international borders is higher in matriarchal societies (such as Nicaragua and Dominican Republic) and lower in those that are patriarchal (such as Mexico and Costa Rica) (Massey et al., 2006; OECD, 2008). Furthermore, being married or in a union greatly reduces the probability of migration for women living in patriarchal societies, while there is no such effect in a matriarchal context.

Share of women in migrant population varies by age (United Nations, 2010a). The share of women is lowest among international migrants aged 30 to 39 and highest among international migrants aged 60 and above. The higher share of women among older international migrants is due to the fact that women tend to have lower mortality rates than men. Among international immigrants of the working age (20 to 64), women slightly outnumber men only in developed countries, while men outnumber women in developing countries. Among older migrants, aged 65 and above, women outnumber men in both developed and developing countries. The excess of older migrant women is more marked in developed countries compared to developing countries.

Highly-skilled emigration rates to developed countries are higher for women than for men for almost all countries of origin, raising concerns about the gender dimension of the brain drain in the less developed regions (OECD, 2008). In particular, average emigration rates of tertiary educated people are much higher for women than for men from Africa and Latin America. For the most part, however, labour market opportunities for migrant women from developing countries tend to be highly concentrated in services and care activities, paid domestic work and the informal sector. These jobs provide low wages, few benefits and limited career opportunities to women, reinforcing their social disadvantages (UNDP, 2009).

Compared to men, women tend to send a larger proportion of their income home, and on a more regular basis, perhaps because of gender expectations regarding the support of parents (UNDP, 2009). However, because women have often lower wages than men, the absolute amounts of money are smaller.

Migration can be an empowering experience for women when they move from situations where they are under traditional, patriarchal authority to situations in which they can exercise more control over their own lives (United Nations, 2006). Migrants may adopt new norms related to higher age at marriage, lower fertility, or greater expectations for their girls’ education and labour force participation. Women may enjoy a more equal distribution of household tasks and greater empowerment in general. These changes are more likely to take place where women are integrated in the host societies and their roles are not limited to housekeeping and child-rearing. Some of the changes may affect not only the immigrants in the host countries but also the communities in their home countries, through a process of cultural diffusion of gender roles and expectations within and outside the family (United Nations, 2006).

In countries of origin, women who remain behind when their husbands or children migrate often have to take on new roles, and increase their participation in decision-making in their households and their communities (United Nations, 2006; UNDP, 2009). Some of these gains, however, may be reversed when the male migrants resume their position as head of the household on return (UNDP, 2009).

International migration statistics produced by a country usually refer to inflows and outflows of international migrants and stocks of international migrants. Who is counted as an international migrant in the official statistics varies across countries, the criteria usually taken into account being the duration of living abroad and either the country of birth or the country of citizenship.

Statistics on flows of international migrants (over the course of a specified period, usually a calendar year):

Number of incoming international migrants by sex, age, country of citizenship and previous country of usual residence. These data can be disaggregated by reason for admission for foreigners or non-citizens, and by purpose of staying abroad for returning migrants.

Number of departing international migrants by sex, age, country of citizenship, future country of usual residence and purpose of migration.

Statistics on stocks of international migrants may be derived by countries based on country of birth or citizenship. Here are some examples of statistics related to lifetime migrant stocks and recent migrant stocks.

Statistics on lifetime migrant stocks:

Population by sex, age, and country of birth.

Population by sex, age and country of citizenship.

Population by sex, age, citizenship status (citizen, foreigner/non-citizen, unknown citizenship) and country of birth.

Number of citizens currently living abroad by sex, age, country of destination and year or period of departure.

Statistics on recent migrant stocks:

Foreign-born population in the country for less than five years by sex, age, and country of birth.

Foreign-born population in the country for less than five years by sex, age, and previous country of usual residence.

Additional breakdowns. When possible, the statistics on international migration stocks should be further disaggregated by marital status, educational attainment, employment status, status in employment and occupation. This will allow assessing gender differences in migration propensity for various population groups; and differences in gender gaps in education and work between the migrant population on one side and, on the other side, the overall population in the country of origin or in the country of destination.

Additional statistics and information necessary to understand the consequences of international migration on families of origin and women’s empowerment:

Number of international migrants sending remittances to their countries of origin by sex of migrant. Additional breakdowns that should be considered are age, duration of staying abroad, marital status of the migrant, and the family relationship of the recipient with the migrant - family member (spouse or children), parent, siblings or others.

Although important, statistics showing the effect of international migration on empowerment of women are more difficult to produce as part of a regular programme of official statistics. When the subject is the empowerment of women migrants, the statistics needed may have to be based on data that are produced both in countries of origin and countries of destinations. Such studies would compare, for example, the demographic behaviour (fertility or use of modern contraception, for instance) of migrant women with the demographic behaviour of women of the same age and educational attainment in the countries of origin. Empowerment of women back home in the community of origin may also be difficult to capture through official national statistics. In this case, more in-depth studies of small areas with high prevalence of international emigration may be a more efficient tool for understanding some of the gender-specific consequences of migration in communities of origin.

Population censuses collect data on international migrant stock residing in the country at the time of census. The characteristics used to identify international migrants in the population censuses include place of usual residence, place and country of birth, place of previous residence, and citizenship. Duration of residence, place of residence at a specified date in the past (such as five years prior to census), or year or period of arrival can be used to identify recent migrants.

Some population censuses collect data related to emigrant stocks, by inquiring about household members living abroad, or country of residence of children or of siblings.

Household surveys specialized on international migration carried out in the country of origin or country of destination can provide in-depth information necessary to understand causes and consequences of international migration. Household surveys on international migration in the country of origin focus on collecting (a) socio-economic characteristics for comparison of emigrants and their households with non-emigrants and their households; (b) basic characteristics of emigrants’ departure; and (c) basic information about remittances sent by the emigrant. In countries with high emigration rates and high return migration rates, more specialized surveys may be conducted to assess the impact of return migration on migrants, their families and their communities.

In the country of destination, household surveys focus on immigrant population. These surveys can collect data on international migration history of individuals, their integration in the host country and more detailed information on remittances sent in the country of origin. It should be noted that household surveys are the only source on sex-disaggregated data on remittances. Specialized surveys on remittances may be conducted in some countries of destination.

Some studies may use a two-country approach in collecting or analysing data on migration, which requires one survey in the country of destination and one survey in the country of origin.

Questions on migration may be included in regular household surveys with large samples, such as labour force surveys, although the number of migration-specific questions that can be added are limited, restricting what can be learned about causes and consequences of migration. The most basic questions on international immigration refer to country of birth, country of residence at a specified time in the past and date of arrival in the host country. Other household surveys such as living standard surveys may also collect data on international immigration or emigration.

Population registers and other administrative registers such as registers of foreigners and registers of asylum seekers, if continuous and complete, are a valuable source of data on international migrant stock and inflows and outflows of international migrants. However, some immigrants may not be recorded in the population registers because they do not have legal permits (illegal immigrants, for example).

Administrative records related to visas granted; work permits; residence permits; and records from regularization programmes provide data that can be used to estimate the flow of certain types of migrants in and out of a country.

Border, admission or passenger records at the entry into or departure from a country are another source of international migration flows for all persons formally entering or leaving a country. Surveys at the border or ports of entry, including passenger surveys, are also used by some countries to collect more in-depth information about persons entering or leaving the country.

In general, data on international migration are lacking in terms of availability and quality. In addition, although data are increasingly made available disaggregated by sex and age, other information necessary to understand gender-specific causes and consequences of international migration are not easily available. For example, data are often not collected, disaggregated and disseminated by reason for international migration, such as labour, asylum seekers, family reunion, or education, which may be different for women than for men. Additional characteristics of the migrants such as education, status in employment or occupation, that may also be different for women than for men, are not readily available either. Finally, information on how women and men migrants are contributing to changes in the families and communities of origin, and how women migrants are affected themselves in terms of empowerment and family life are rather the result of a few case studies than of regularly produced official statistics.

Data on lifetime migration and migrant stock as opposed to recent migration tend to overestimate the share of women among migrants, because of the ageing effect. The share of women in a given age-cohort of migrants will increase over time simply because women tend to have lower mortality rates than men. Therefore, data on lifetime migration should be disaggregated by age or, alternatively, data on recent migration should be used. Focusing on lifetime migration may also provide an incomplete picture of gender differences in migration, when short-term migration, temporary migration, or circular migration tends to be associated with one of the two sexes.